Writing your C++ DLL code

To create a simple C++ DLL:

Ensure that classes and class members are exported correctly, especially if they use templates.
Use _Export or the #pragma export directive to export specific functions and variables.
For example, to create a DLL executable module TRIANGLE, export the getarea() function, the getperim() function, the static member objectCount and the static constructor for class triangle using #pragma export:
Figure 1. Using #pragma export to create a DLL executable module TRIANGLE
```
   class triangle : public area
   {
      public:
         static int objectCount;
         getarea();
         getperim();
         triangle::triangle(void);
   };
   #pragma export(triangle::objectCount)
   #pragma export(triangle::getarea())
   #pragma export(triangle::getperim())
   #pragma export(triangle::triangle(void))
```

Do not inline the function if you apply the _Export keyword to the function declaration.

Figure 2. Using _export to create DLL executable module TRIANGLE

   class triangle : public area
   {
      public:
         static int _Export objectCount;
         double _Export getarea();
         double _Export getperim();
         _Export triangle::triangle(void);
   };

Always export static constructors and destructors when using the _Export keyword.

Apply the _Export keyword to a class. This keyword automatically exports static members and defined functions of that class, constructors, and destructors.

   _class Export triangle
   {
      public:
         static int objectCount;
         double getarea();
         double getperim();
         triangle::triangle(void);
   };

To export all external functions and variables in the compilation unit to the users of this DLL, you can also use the compiler option EXPORTALL. This compiler option is described in z/OS XL C/C++ User's Guide, and #pragma export directives are described in detail in z/OS XL C/C++ Language Reference. If you use the EXPORTALL option, you do not need to include #pragma export or _Export in your code.